# Questions tagged [beam]

Questions about the theory and applications of structural elements designed to resist bending.

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• 111
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### Bolted plate static and dynamic friction explanation

I will not go into the exact details of the engineering problem. Still, I kindly ask for some help with a proper explanation because I am having trouble explaining the correct principle in this ...
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### Normal Weight of RC Beam

Is 450kg/m for a reinforced concrete beam outlandish? The dimensions are: width: 0.3m depth: 0.6m I am designing a beam, and that is what I got.
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1 vote
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### What load would a 2" x 4' x 8' sheet of pink XPS foam wrapped in fiberglass using epoxy resin support if used as an 8' bridge?

I need to build a light weight ramp roughly 4' wide by 8' long. I've built similar out of 1/2" plywood and 2x4s. That's plenty strong but much too heavy. If I wrapped a 4' x 8' sheet of 2" ...
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### Steel beam splice design

What is a good source of design recomendations for beam splices? I'm designing a structure and I need some help with getting proper splice strength for certain beam size. To make it simpler, I need ...
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### Calculating deflection of a cantilever beam using Young's modulus

I have looked at a lot of deflection questions on here and I didn't see anything that quite matched what I needed to know. I am working through some curriculum for students and I am working through ...
• 101
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### Do tensile and compressive stresses create moments?

Below are 3 examples I designed. My question is about the tensile and compressive stresses that occur in 3 examples under the influence of a horizontal force F=100N (earthquake force). I ask my ...
67 views

### Static Equilibrium of Rigid Bodies

When we talk about the idea of static equilibrium in engineering mechanics we consider the idealized case of a body which is a rigid body, meaning it cannot deform. Then we solve for the 3 equilibrium ...
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### Why don't we calculate buckling in composite beams?

I have a frame, it consists of steel beams and my flooring is a composite deck. It consists of composite beams that are hinged to my steel frame beams. Composite beams do not transfer moments. Now, ...
91 views

### Calculate the deflection of a fixed supported beam

I am having a lot of trouble with the below question. Im not really sure how to calculate the deflection of the x coordinate, how do i go about completing this question? Any help would be appreciated ...
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### FInding deflection on a uniform beam with supports ~ Incorrect answer

Hello I am asked to find deflection of beam in millimetres at different points. The uniform beam is 3.55 meters long with a flexural rigidity of 32269Nm^2 It is under a uniform load of 92N/m and is ...
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### Finding deflection on a uniform beam with fixed supports ~ Incorrect answer :(

This question has asked us to find the deflection of a beam (in millimeters) if the beam is under a load of: f(x) = 9.46(x+0.82)(9.2288-x) N/M The beam is supported with fixed supports at both ends ...
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### How can I mount this plate on a Steel Beam?

As mentioned in the question, I am looking for a method to attach this mounting bracket to the flange of a steel beam that permits effortless removal and remounting without permanent fixation.
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### How to suppress longitudinal stress waves in a beam in FEA

When simulating a bending beam in FEA mimicking the textbook model and approach, unwanted stress waves appear. How to suppress longitudinal stress waves in a beam in FEA? To add friction/damping?
• 101
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### Analysis of beams and supports

In beams when we are converting uniform disturbed load to point load, the point load is assumed to acting at the centre of length why is it so? And converting uniform varying load we assume it to act ...
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### Which beam deflects and twists more, open section or closed section?

Two beams, one open section (like an I-beam with flanges and web) and the other closed section (like a hollow square section) are cantilevered and have the same overall cross sectional moment of ...
• 1,365
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### Derivation of the fundamental principle in the mechanics of beams

Can someone provide the derivation for the following equation: $$\int_l Q_Z(x) dx = M_y (x) \tag1$$ or equivalently : $$\frac{dM_y}{dx}=Q_Z\tag2.$$ I am interested in the $1D$ isotropic material ...
• 119
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### Is there explicit expersion for the natural frequency of a cantilever timoshenko beam?

I am trying to find a closed form solution for the natural frequency of cantilever Timoshenko beam. In mechanical vibration (Rao, 5th edition) he outlined the details to include the Effects of Rotary ...
• 113
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### Shape of a beam that is bowed under compression?

Suppose you have a uniform beam, such as a piece of plywood that is 4 feet long, six inches wide, and half an inch thick. Suppose you cause it to bend by attaching, for example, a string under ...
• 121
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### Multiple varying cross section beam with distributed load - FBD Method?

Based on the 2 different threads read below : Multiple Varying cross section beam deflection + Multiple varying cross section beam with uniform loads I'm trying to set up a calculation sheet (Excel is ...
255 views

### How much weight can aluminum square tube support?

I'm building a bed platform in a campervan and trying to determine what type of aluminum tube to buy. I'm thinking to purchase 6061-T6511 aluminum Square Tube with 1.5" width, 1.5" height ...
• 101
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If we take the moment about A from the $F_{BC}$ will make the body want to rotate counter clock wise but If we take it from the point C it will make the body rotate clock wise whats the mistake?
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### Uniform Direction for Line Directions

Despite several similar questions and my efforts, there is still no solution so far. Presently, ANSYS gives Directions to Lines on its own which are flipped even for two collinear lines. As a results ...
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### Need to Align Line Directions Normals Along Specific Coord in APDL

In Preprocessor of APDL, I have built areas which are meshed with shell element and lines meshed with beam elements. I have assigned Sections to Beam elements but when I view them their cross sections ...
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### Mass Brick Settling Causing Excess Load On Center Beam

I live in a 115+ YO building and recently had my kitchen remodelled. During this the subfloor was replaced (old 1x6s in bad shape). I noticed a significant bow in the joists with the central steel ...
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### Is bending stress over round thin-walled tube cross section linear?

It is thin walled because roughly d=200mm and t=6mm of a carbon fiber wrapped tube. The question is, if the bending stress $\sigma$ over the cross-section (in y-direction) is linear or not. It is ...
• 103
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### Need to find beam deflection of a steel tube

So I have a square tube of 40mm, 3mm wall thickness with a length of 1 meter. Both ends are fixed 25mm inwards. Load is 3kg centerpoint. Steel is SJ235. I need to know the deflection of this beam. ...
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### Setting direction vectors for Lines in ANSYS APDL

I am using beam elements to mesh lines with "pre-meshed" shell areas. Problem is that the ANSYS sets Line Direction vectors on its own. This results in Cross sections assignment flipped from ...
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### Can someone help me with solving this beam problem using Rayleigh Ritz Method, my trial function is not working

The question is there is a two element beam joined together. The first element is 5m long and the other is 4m long. At the outer nodes there are roller supports and at the middle point where two ...
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### Shear Force in Inclined Beam

Suppose I have an inclined beam with a UDL applied vertically downwards, will the shear force act normal to the beam, or vertically?
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### Justification for choice of beam stiffness at pinned far-end member

I’m reading off an example provided by the ICE structural analysis book, specifically example 4.7 (moment distribution method) I dont seem to understand why the stiffness from member D-C is 4EI/L ...
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### Beam deflection for FEA model validation

I'm trying to validate an FE model that I'm using by comparing to a simplified analytical solution to the problem. The part I'm analyzing is a lug that is constrained on one end and has a point load ...
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### Mechanics of Materials Method for Curved Beam with Different Centers

The common curved beam theory covered is the Winkler method (e.g. in Johnston and Beer, or Boresi and Schmidt). As can be seen by reading any derivation, this method applies to beams with a common ...
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### Rigid frame deflection and material selection

I'm building a frame that will receive a point load mid span (likely it won't be but want to design for worse case). The frame is 1.5 x 0.095 square tubing, and it will be skinned with 14ga on one ...
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### The Effect of Accelerometer Position on Modal Analysis of a Cantilever

We have obtained the first two vibration modal frequencies of a composite cantilever (33 gm). We placed the accelerometer (3.4 gm) near the fixed end and the two frequencies were F1=30 Hz and F2 = 256 ...
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### Ratio of length to baseplate bolt pattern to assume that a joint is pinned

I have a truss tower that is attached to a hoist arm by a baseplate. The truss tower is 80ft long and the bolt pattern of the baseplate is a 1ftx1ft square. Is it valid to assume that the joint ...
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### Which formula to use to calculate the main vibratory frequencies of a wooden joist floor? (8 Hz?)

When a wooden floor joist is a little undersized, there is a vibration phenomenon when walking on the floor. In some forums, I've often seen a frequency of 8 Hz mentioned when walking on the floor, ...
• 101
1 vote
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### Extension of a cantilever beam composed of unbonded layers

The question of the magnitude of the vertical deflection of a cantilever beam composed of unbonded layers has been posted here, but I was wondering if there is an analytical way to solve for the end ...
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### Shearing Stress in a Beam with Torsion

In "Theory of Elastic Stability" by Timoshenko and Gere, the authors say for a beam in pure torsion, For a beam of thin-walled open section it can be assumed with reasonable accuracy that ...
• 147
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### Benchmarking Geometrically Exact Beams: Clarification Needed on Material Density?

In an early paper on Simo, I came across an example titled "Cantilever 45-degree bend subject to fixed and follower end load". A force of $600N$ and $300N$ was applied at the end, resulting ...
• 103
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### Warping deformation for arbitrary cross-section under torsion

Title says it. I wish to learn the approach for programming (with FE, or with alternative discretized models) the warping deformation for each point in an arbitrary cross-section, knowing the contour ...
• 121
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I have the following equation for calculating the Admissible shear stress for a uniformly distributed load. $$\tau_{adm} = \frac{3}{2}\cdot \frac{F\cdot L}{2b\cdot h}$$ where $F$ = kN/m $L$ = ...
• 101
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### Load distribution for a load centered over the length of the middle joist in a 3-joist system

I'm not an engineer, but I'm trying to understand the correct analysis for what seems like a pretty simple case. I'd like to know what the effective load on the middle joist is. ...
88 views

### Determine the temperature required for expanding or bending?

Is there any possible way to calculate the temperature required for a metal to expand or bend with dimensions? For example, take Mild steel with a length of 100mm, width of 150mm, and thickness of 2....
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### How can I calculate the maximum center load on a horizontal cellular glass tile; supported along its edges, before it breaks?

Insulating cellular glass boards or tiles are designed to sit on a flat load-bearing surface. I want to consider the situation where the base is concave so the tile is only supported on its edges. I ...
137 views

### Determining the critical load of a fixed beam with non-uniform cross-section?

I am a computer scientist, not a mechanical engineer, so it is absolutely possible that I am missing some basic understanding here. I have a beam that is fixed in both ends and my goal is to ...
• 101
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### Theory of large deflection of (cantilever) beams

As the simplified theory of beam deflection, taught in typical mechanical engineering courses (in Germany its called first order theory), is limited to small deflections, I want to look into the ...
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### Optimal shape for cantilever beam subject to body weight only

How can I find the optimal shape of a cantilever beam subject only to its own weight, and having the following restrictions? The cross section is a rectangle Only the height of the rectangle can vary ...
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### Spring constant of angled beam

I'm trying to solve for the dynamics of three blocks, shown below. Two blocks are pushed into a central shuttle, and their force is transmitted through a thin angled beam/pawl. The pawl bends when ...